Cyclone separator



Oct. 30, 1962 J. MORAWSKI CYCLONE SEPARATOR 6 Sheets-Sheet 1 Filed Feb.29, 1960 INVENTOR.

JU LIAN MORAWSKI ATTORNEY Oct. 30, 1962 J- MORAWSKI 3,060,554

CYCLONE SEPARATOR Filed Feb. 29, 1960 6 Sheets-Sheet 2 INVENTOR. Jim/41vMoeiwrz/ 1952 J. MORAWSKI 3,060,664

CYCLONE SEPARATOR Filed Feb. 29, 1960 6 Sheets-Sheet 3 I NV EN TOR. Juzmw MOZflM/JZ/ Oct. 30, 1962 J. MORAWSKI CYCLONE SEPARATOR 6 Sheets-Sheet4 INVENTOR JULlAN MORAWSKI W%% I ATTORNEY Filed Feb. 29, 1960 F1 .13

Oct. 30, 1962 J. MORAWSKI CYCLONE SEPARATOR 6 Sheets-Sheet 5 Filed Feb.29, 1960 ATTORNEY Oct. 30, 1962 J. MORAWSKI 3,060,664

CYCLONE SEPARATOR Filed Feb. 29, 1960 6 Sheets$heet 6 INVENTOR. JULIANMORAWSKI ATTORNEY United States Patent ice.

3,060,664 CYCLONE SEPARATOR Julian Morawski, 448 35th St., ManhattanBeach, Calif. Filed Feb. 29, 1960, Ser. No. 11,760 21 Claims. (Cl.55-431) This application is a continuation in part of my copendingapplication, Serial No. 712,848, filed February 3, 195 8, for CycloneSeparator.

This invention pertains to a device for separating solid particles fromgaseous suspension, and more particularly to separators of thecentrifugal or cyclone type.

The desirability of removing solid particles from gases emitted into theatmosphere of industrial areas is well known. Damage to vegetation andbuildings can be extensive, while the health of the residents may beadversely afiected. Cleaning of gases discharged into the atmosphere,therefore, has become recognized as a necessity in the presentindustrialized society.

One of the simplest and most economical to construct and operate of thevarious known separating devices is the centrifugal or cyclone type ofseparator, wherein the dust laden gases are rotated at high velocitythus permitting removal of the heavier solid particles by centrifugalforce. However, the inability of these devices to remove particles of avery fine size, and their relatively low efficiency and lack ofconsistency in separation even of larger particles, has limited the useof cyclone type separators. Many efiorts have been made to improve theperformance of these units, such as by conducting portions of the gas toauxiliary separating devices, or by including various baflles in thehope of altering the flow within the separator in a manner which wouldimprove the ability of the separator to remove dust from the gas. Theseschemes have increased the size and complexity of the separatorassemblies, yet have not materially added to their efilciency.Therefore, cyclone separators have not been utilized where topperformance is required.

It has been possible to remove the greatest percentages of particulatematter by means of electrical devices which precipitate the solidparticles from the gas. However, these electrical separators areextremely costly to purchase and maintain. Many of them will not operateproperly on heavy dust concentrations and require additional units inthe form of mechanical separators for precleaning the gas before it issent to the electrical precipitator. Another factor adding to the sizeand expense of the electrical separators is their requirement for lowgas velocities past the electrodes. Furthermore, these units do notoperate properly at elevated temperatures which in many instancesnecessitates the provision of extra equipment for cooling the gases.Also, corrosive gases or liquids materially shorten the life of theelectrodes and reduce their eifectiveness. Furthermore, while theseelectrical separators are generally efficient in their separation ofmost solid particles from the gases, they are somewhat less effectualfor gases containing dusts with high concentrations of carbon.

Other separating devices also have inherent shortcomings. The bag type,having fabric filtering media, cannot be used for high temperature gasesand requires low gas velocities. These devices are subject toconsiderable wear and consequently have a short life and require highmaintenance expense.

Gas washers and scrubbers also are utilized in cleaning gases, but theydemand a large supply of water which is not always available. Also, theyrequire compressors, pumps, driving machinery and the like, all of whichinvolve expense, maintenance difliculties and space requirements.Disposal of the slude produced by these separators presents atroublesome problem.

3,060,664 Patented Oct. 30, 1962 The device of this invention provides acyclone separator having the advantages of simplicity and economy thatare possible with such units. Its efliciency is far superior to theusual cyclone separator, and is on a par with that obtained byelectrical separators. However, unlike electrical precipitators, itsperformance is not impaired when carbon particles are found in thegases, but all materials are removable regardless of their chemicalcomposition. The temperature of the gas or its corrosiveness likewisedoes not limit the effectiveness of the device of this invention. Theseresults are achieved by providing a special annular passageway aroundthe gas outlet for the unit to receive gases highly laden with dust,which then are conducted automatically to the bottom portion of thecyclone and discharged in a rotational pattern at the location withinthe cyclone of highest separation efiiciency. -Preferably, the annularpassageway is in the form of a diifuser to eifect maximum pressurerecovery and increase the pressure gradient that causes the by-pass flowof gases to the bottom of the separator. Additional baffles may beincluded to deflect the solid particles in the gas to the annularpassageway, and means may be provided to inject a driving fluid in arotational path at the area below the gas outlet in order to increasethe velocity rotation at that point and hence the efficiency ofseparation.

Accordingly, it is an object of this invention to provide an eflicient,simplified, low cost cyclone separator.

Another object of this invention is to provide a cyclone separatorhaving means for increasing the velocity of rotation of the gaseslocally within the cyclone body, but requiring no moving parts.

A further object of this invention is to provide a cyclone separatorwhich takes advantage of the natural flow phenomenon inside of theseparator to remove gases having heavy dust concentrations from the areaof the gas outlet, and discharge these gases in the portion of theseparator of most efiicient operation and in such a manner as toincrease the rotational velocity within the separator.

An additional object of this invention is .to provide a cycloneseparator having provision for recirculating dust-laden gases in orderto increase the probability of separation of particulate material.

Another object of this invention is to provide a separating devicehaving provisions for adding a driving fluid for increasing the velocityof rotation of the mass within the separator.

Yet another object of this invention is to provide a separator havingdeflectors arranged to divert solid material away from the center of thegas outlet, and having an intercepting bypass arranged to receivematerial so deflected.

A still further object of this invention is to provide a separatorhaving means for increasing the velocity of rotation locally in thevicinity of the gas outlet.

Yet another object of this invention is to provide a separator havingmeans for bypassing particulate material, which normally would enter thegas outlet at the upper end of the housing, to the lower end of thehousing for separation from the gas and entry into the hopper.

An additional object of this invention is to provide a cyclone separatorhaving means for imparting a helical pattern of rotation in the vicinityof the inlet to reduce interference and turbulence at the inlet scroll.

Yet another object of this invention is to provide a cyclone separatorwhich subjects the gas to only a very low pressure loss.

Still another object of this invention is to provide a cyclone separatorhaving a lower cut size of removable particles than conventional design,and c apgble of removing a higher ercenngear particles above the cutsize than'can be'accomplished by other separators.

A further object of this invention is to provide a cyclone separatorcapable of separating out solid or liquid particles of low density andof diameters under ten microns.

These and other objects will become apparent from the following detaileddescription taken in connection with the accompanying drawing in which:

FIG. 1 is a schematic illustration showing the flow pattern with acyclone separator,

FIG. 2 is a schematic view similar to FIG. 1 depicting the tangentialvelocity and static pressure values found within a cyclone separator,

FIG. 3 is a schematic view similar to FIGS. 1 and 2 showing theefliciency of separation at various locations within a conventionalcyclone separator,

FIG. 4 is a side elevational view of the separator of this invention,

FIG. 5 is atop plan view of the arrangement of FIG. 1,

FIG. 6 is an enlarged longitudinal sectional view taken along line 6-6of FIG. 5,

FIG. 7 is a fragmentary side elevational view illustrating the helicalwall at the entrance to the separator of this invention,

FIG. 8 is a fragmentary sectional view of the bypass discharge nozzletaken along line 8-8 of FIG. 6,

FIG. 9 is a fragmentary sectional view showing a modified form of bypassinlet arrangement,

FIG. 10 is a fragmentary view similar to FIG. 9 of a furthermodification of the bypass in which no difiusion takes place,

FIG. 11 is a longitudinal sectional view similar to FIG. 6 showing anarrangement in which a means for deflecting particles to the bypass andfor locally increasing the velocity of rotation is included,

FIG. 12 is an enlarged sectional view taken along line 12--12 of FIG. 11illustrating the discharge nozzles for the driving fluid used in locallyaccelerating the flow velocity,

FIG. 13 is a fragmentary sectional view of a further modification inwhich dual bypass inlets are included,

FIG. 14 is a fragmentary sectional view of a dual bypass unit which alsoincludes an element for deflecting particles outwardly toward the bypassopenings,

FIG. 15 shows a further modification of a dual bypass unit,

FIG. 16 is a fragmentary view of a modification of the arrangement ofFIG. 15 to include an annular element around the central deflectingmember,

FIG. 17 is an enlarged fragmentary view of an arrangement similar toFIG. 16, but including means for locally increasing the velocity ofrotation at the axis of the outlet members, and

FIG. 18 is an enlarged sectional view taken along line 18-18 of FIG. 17showing the arrangement of the manifold and the discharge nozzle for thedriving fluid.

The provisions of this invention can best be understood by consideringbriefly the flow phenomena present in and inherent to cyclone separatordevices. In a typical cyclone separator, such as shown schematically inFIGS. 1, 2 and 3, the dust laden gas enters the separator through ascroll 1 leading into the upper cylindrical portion 2 below which is afrustoconical section 3. The bottom end of the latter communicatesthrough opening 4 with hopper 5 which is to receive the separated dustparticles. An outlet tube 6 extends into the upper end of the unit anddischarges the cleaned gas.

When the gas is discharged in a rotational pattern by inlet scroll 1, avortex is produced within the housing, limited in diameter by the outerwalls 2 and 3. Also, there is a downward component of velocity movingthe rotating mass along the walls toward the bottom of the unit andoutlet 4 (see FIG. 1). A center column of gas rises upwardly from thebottom of the unit, moving along the axis of the housing into outlet 6.Some eddies from the downwardly moving material also circulate inwardlyand enter the central core of rising gas, to be drawn into outlet 6.

In addition to this overall pattern, there is present a rotatingdoughnutshaped ring of gas at the upper end of the housing around outlettube 6, resulting from the geometry of the scroll inlet and theproximity of the gas outlet tube. In addition to the rotational movementof this annulus, there is local circulation about its circumferentialaxis. This movement is downward adjacent tube 6 and upward at thelocation of the outer wall 2.

The underlying principle on which all cyclone separators operate is thatthe particulate material, being heavier than the gas, is driven to thehousing walls 2 and 3 by the centrifugal force resulting from theoverall rotational pattern. There the particles are carried by thedownward velocity component into outlet 4 and hopper 5.

In its relative outward motion under the influence of centrifugal force,the solid particle is also subjected to an opposing drag force exertedby the gas and tending to drag the particle through outlet 6 along withthe gas. It is apparent that the centrifugal force on the smaller andthe less dense particles will not be as great as the centrifugal forceon the larger and heavier particles. Therefore, at some critical pointin particle size, the centrifugal force will not able to overcome thedrag on the particles caused by the radial currents of gas entering thecentral column of gas rising to outlet tube 6. Such smaller particles,therefore, cannot be separated, but will leave the unit along with thegas. This minimum size of separable particles is known as the cut of theseparator.

All particles larger than this diameter should be removed from the gasstream. However, all cyclones of conventional design suffer from aninherent and objectionable characteristic in that they allow a largenumber of particles bigger than this limiting size to pass to the gasexhaust with the cleaned gas and hence lower the separation efliciencyof the apparatus.

As a result of the flow pattern within the cyclone and the forces actingtherein, the tangential velocity of the rotating mass will exhibit thecharacteristics indicated by curves A1, A2, A3, A4 and A5 in theschematic representation of FIG. 2. It can be seen from thisillustration that throughout the housing the tangential velocityincreases as the axis of the housing is approached, dropping off only atthe location of the central upwardly moving core of gas. Near the bottomof the housing, where the gas becomes more constricted by the walls 3 ofthe housing, the tangential velocity of the gas becomes greatest. Thelowest tangential veolcity is indicated in curve A1 adjacent outlet tube6. In other words, at the latter location the radial component ofvelocity will be greater in proportion to the tangential velocity thanelsewhere within the housing.

The static pressure within the separator is indicated by curves B1, B2,B3, B4 and B5 of FIG. 2, having a maximum value at Walls 2 and 3 anddecreasing toward the axis of the housing. In addition, there is avertical pressure gradient, with the static pressure near the bottom ofthe unit, where the swirl velocity is greatest, being at its minimumvalue, ranging to the highest static pressure near the top of the unit.Thus, in general it can be said that at the top of the housing in thevicinity of the outlet for the gas, the lowest tangential velocity isaccompanied by the maximum static pressure, and at the opposite endWhere the tangential velocity reaches its highest value the staticpressure is at its minimum.

As a result of the phenomena discussed above, the efficiency of acyclone separator in removing particles from the gas varies widely atdifferent locations within the separator. This is graphicallyrepresented in FIG. 3 where a plurality of iso-efiiciency curves isplotted for different positions within the separator. It may be seenthat curve C1 adjacent outlet tube 6 represents an efliciency of only20%, While a short distance below, as represented by curve C6, theefiiciency of separation has reached almost 100%. Thus, by their nature,cyclone separators have the ability to separate most solid particles,except near the outlet for the cleaned gas. It is in this critical areathat the overall efiiciency of conventional units is greatly impaired.

There are two principal reasons for the extreme reduction of efficiencyas the gas outlet of the separator is approached. One is because, asdiscussed above and shown in curve Al, the tangential velocity componentadjacent outlet tube 6 is relatively low. This means that thecentrifugal force, and thus the force urging the solid particles towardthe outer wall of the housing and away from the central gas outlet, isat a minimum value. Therefore, with a reduced centrifugal force urgingthe particles outwardly, they can be more readily swept along with thegas entering outlet tube 6.

The other and perhaps even more important factor results from therotating annulus formed near the inlet where the gas is filled withunseparated particulate material. With the fiow pattern within thisrotating ring passing upwardly along wall 2, inwardly across end wall 7and downwardly around the outer surface of outlet tube 6, particleswithin this ring will be thrown against walls "2, 7 and 6 by centrifugalforce. The rotation about the circumferential axis of this annulus willcause such particles to creep along these walls until the entrance totube 6 is reached. At this point these particles will be drawn intooutlet 6 by the strong upward currents entering this tube.

These two factors of the lowered tangential velocity and the centrifugalforce within the rotating ring are the principal causes of the poorefiiciency in the vicinity of the gas outlet. Their result is that manyparticles larger than the cut size of the separator will leave the unitthrough the gas outlet. Thus, conventional cyclones have fallen farshort of their theoretical ability to remove solid matter from the gas.

The device of this invention is designed to materially increase theefliciency at the critical area near the gas outlet, augmenting therotational speed and precluding the entrance of dust laden gas from therotating ring into the outlet tube. In accomplishing this, the naturalstatic pressure gradient between the top and bottom portions of thehousing is utilized in causing an automatic circulation withoutsignificant frictional losses.

With reference now to FIGS. 4 through 8, the improved separator of thisinvention includes a housing 10 having a relatively short uppercylindrical portion 11 connecting to the lower frustoconical section 12as in conventional designs. An inlet scroll 13 admits the dust laden gasto the separator at the upper end of the cylindrical section, while atthe bottom of the housing outlet 14- leads to a hopper 15 where theseparated dust is to be deposited. In the embodiment illustrated, scroll13 discharges in a clockwise direction as viewed in top plan.

As one of the features of this invention, inlet scroll 13 includes alower wall 16 inclined inwardly to join the cylindrical section along ahelically arranged connecting line 17 as best seen in FIGS. 4, 6 and 7.The lower end 13 of wall 16 merges into the cylindrical section at alocation immediately below where the scroll discharges into the housing.This enables the inlet gas to smoothly enter the rotating mass withinthe housing reducing turbulence and pressure losses, and improving theflow pattern. Thus, as the gas is conducted into the housing, it isdirected downwardly by wall 16 to avoid interference with the incominggas leaving scroll 13.

In the arrangement of FIGS. 4 through 8, a frustoconical exit tube 26extends axially downward into the top end of the housing for receivingthe central core of cleaned gas and removing it from the housing.Sturounding exit tube 20 is an additional frustoconical tubular element21,

6 the bottom edge 22 of which is below bottom edge 23 of member 20.

On the exterior of exit tube 20 is an outwardly flaring portion 24joining a substantially cylindrical portion 25. This causes arestriction in the portion of passageway 26 between members 20 and 21where sections 24 and 25 meet, while the upper end of this passageway isdivergent in cross sectional area in view of the outwardly taperingnature of member 21.

An outlet 27 is provided for the upper end of member 21 connectingthrough elbow 28 to a tube 29 which extends downwardly to the lower endof the housing section 12. Tube 29 terminates in a convergent nozzle 30inclined downwardly and arranged to discharge tangentially along theinner wall of the lower end portion of the conical section 12 of thehousing, as best seen in FIG. 8. the direction of discharge of nozzle 30is the same as that for scroll 13, being clockwise as seen from above asin FIG. 5.

Some latitude is permitted in the positioning of nozzle 3-0, butparticularly satisfactory results have been obtained when it is locatedabove outlet opening 14 a distance equal to one-half to four times thediameter of this aperture. Also, it is preferred to incline the nozzledownwardly so that angle alpha with respect to the horizontal plane ofthe separator, is within the range of live degrees to twenty degrees. I

Several important advantages are realized by this construction,resulting in eificiency far superior to anything previously obtainablein a separator of this type. It may be noted that the bottom end 22 ofthe outer tubular member 21 is located in the zone of minimum separationefiiciency of the cyclone unit. As discussed above, the central columnof upwardly rising cleaned gas tends to pick up solid particles from thegas near the gas outlet where the rotational velocity is relatively slowand hence the centrifugal force on the particles is at a minimum.Further, solid particles tend to enter the outlet tube from the rotatingring within the scroll area.

However, as the particulate material within the body of the separator isdrawn toward the periphery of the central core of upwardly moving gas,it will enter outer tubular member 21 and be bled ofi through thepassageway 26 instead of leaving the housing through the gas outlet.Also, the particles which creep along the walls near the gas exit due tothe rotating ring at the area, will move downwardly along the exteriorof tube 21 to its lower end 22. There these particles will be drawn intothe bleed passageway 26 instead of entering gas exit tube 20. Therefore,the annular passageway 26 between members 20 and 21 will receivevirtually all of the solids in the gas, to bypass them through conduit29 to nozzle 30. The outwardly flaring portion 24 on the exterior oftube 20, and the resulting restriction in the passageway caused thereby,tends to increase the upward velocity of the peripheral gases at thispoint, helping to draw the particulate matter into the annular areabetween the two tubular sections. Outwardly flaring portion 24 alsohelps to physically deflect the particles into this passageway.

As discussed above, a characteristic of a cyclone type separator is theexistence of a pressure differential between the top and the bottomportion of the housing. This pressure differential is utilized indrawing the heavily dust laden gases into the passageway 26 betweenmembers 20 and 21 and conducting them downwardly into the bottom end ofthe housing. In view of the lower pressure at the bottom end of thehousing, a natural circulation will be provided, automatically suckingthe dust and gases from the annular area around tube 20 and conductingthem to the bottom of the housing. Thus, no moving parts or auxiliaryequipment are necessary for withdrawing the mixture of dust and gas fromaround the central clean core and discharging it into the lower end ofthe housing.

The position of nozzle 30, by being tangential to the wall at the lowerend of the housing, causes the gas discharged from the nozzle to swirlin a rotating pattern. This reinforces the natural rotation of the gaswithin the housing and augments the tangential velocity that isobtained. Hence, the discharge from nozzlze 30 serves to increase therotational speed of the mass within housing 10, even further raising theefficiency of separation of particulate matter from the gas. As aresult, the cut of the separator is shifted to a lower range of particlesize. This enables the device not only to obtain a higher degree ofseparation for the particles within the housing, but also to separateparticles of even smaller size than would otherwise be possible. Thus,the gas with the heavy dust concentration discharged from nozzle 30 isrotated at an exceptionally high speed so that nearly all of theparticulate material will be separated, driven against the walls of thehousing and conducted downwardly into hopper 15.

If any residual particles remain within the gas rising from the bottomof the housing, they again may be diverted into the passageway 26between members 20 and 21 and reconducted to the bottom of the housingfor separation. There is no limit to the number of times that thepatriculate material may be so circulated through the unit, and as aresult, the possibilities for separation from the gases are greatlyenhanced. This is especially true since during the recirculation processthe very fine particles can grow in size by coagulation due to impact,electrostatic charges and the like.

The slight downward inclination of nozzle 30 assists in correctinganother shortcoming of most cyclone separators. Under many conditionswhere heavily laden gases are to be cleaned, the dust will accumulatearound the outlet from the conical portion, choking this opening andpreventing any further discharge into the hopper. However, by incliningnozzle 30 downwardly, the discharge from the nozzle is blasted towardthe opening 14 and always maintains this opening free of any congestion.There will be no choking of outlet 14 when the nozzle 30 is given asinclination in that direction. Therefore, for maximum efliciency it isimportant to discharge the bleed dust and gas both in a rotationalpattern in the bottom of the housing, and toward the hopper entrance.This assists the natural flow pattern within the housing, avoiding thecreation of turbulence or pressure losses, increasing the velocity ofrotation and improving the ability to separate particular matter, whileassuring that no choking of the dust outlet can occur.

The diverging portion of the passageway 26 between members 20 and 21,above the restriction caused by member 24, causes the passageway to actas a diffuser. This permits eflicient pressure recovery, raising thestatic pressure at the upper end of this passageway without unduelosses. Therefore, the pressure differential between the top and bottomportions of the cyclone is increased so that there is an even greatertendency for the material around member 20 to be drawn into the annularpassageway and conducted to the lower end of the housing. A head of fromtwo to five inches of water will be maintained to cause the automaticflow through the bypass. Normally from five to twelve percent by volumeof the gas will be recirculated in this manner. Although not usuallyrequired, a valve 31 may be included in line 29, if desired, to controlthe bypass flow.

Primarily to decrease the cost of manufacture of the unit by simplifyingits construction, the upper portion of the device may be constructed asindicated in FIG. 9. This includes the provision of concentricfrustoconical tubular members 32 and 33 for the gas outlet and bypass,respectively. According to this design, however, the frustoconical shapeof the gas outlet member 32 is retained on both its interior andexterior surfaces. This means that there is no constriction in thebypass passageway 34, and no outwardly flaring surface at the intakeportion of the gas exit member for deflecting the solid particles intothe annular passageway. However, the diverging nature of the bypass 34causes it to act as a diffuser, resulting in an efficient pressurerecovery and an increased pressure differential between the top of thebleed passageway and the location of the nozzle at the bottom end of thehousing. This modification, therefore, is only slightly less efficientthan that of the previously described embodiment.

An even more economically constructed unit is illustrated in FIG. 10where both the gas outlet member 37 and the outer bypass tube 38 aresimple, straight-sided cylindrical members. While the device willfunction essentially as described before in drawing the dust laden gasesfrom around the perimeter of the clean gas outlet, the cylindricalmember 38 does not act as a diffuser. This means that there is noincrease in pressure differential between the top and bottom of theunit, and also that some added pressure losses may be expected from theflow of gases through the bypass assembly. This embodiment, therefore,normally will be selected where separation requirements are lessexacting and construction at a minimum cost is a primary objective.

Particularly useful for more sizable units where large volumes of gasesmust be handled is the arrangement illustrated in FIGS. 11 and 12. Insuch separators the tangential velocity of the vortex at the entry tothe cyclone usually is relatively low, being less than the linearvelocity of the inlet duct. Because of this and to avoid excessivepressure losses, the ratio of the housing diameter to the diameter ofthe outlet tube must be kept relatively small. Therefore, angularvelocities in the vicinity of the gas outlet, and consequently thecentrifugal force acting on the solid particles, do not reach a highvalue. Even with provision for external means to accelerate the angularmomentum of the entire mass within the separator, with consequent largeexpenditure of energy, adequate velocities often are unattainable inconventional designs.

These problems of large separators are overcome by the provisions shownin FIGS. 11 and 12, where the annular bypass provided around the gasoutlet may be constructed generally as in any of the previouslydescribed designs. Typically this includes a frustoconical exit member39 for the gas at the axis of the housing, surrounded by a largerfrustoconical tube 40 to define an annular passageway 41 for connectionwith bypass line 29. Lo-

- cated generally beneath these members, within cylindrical extension 42depending from member 40, but in the upper portion of the housing, is anadditional unit 43 which performs two functions in further augmentingthe efliciency of separation. First, this unit includes a dependingconical end 44 at the axis of the housing which presents a surface whichacts as a deflector to direct any particulate material remaining in thegases outwardly toward the inlet to the annular passageway 41 betweenmembers 39 and 40. Any solid particles which contact the surface ofportion 44 will be forced outwardly and virtually to the radial positionof the inlet to this annular passageway so that the natural tendencywill be for such particles to enter the bypass to be conducted into thedownwardly extending tube 29.

In addition, a provision is made to discharge a driving fluid into thehousing at the location of member 43 for increasing the rotationalvelocity at that location. As discussed above, this member is positionedgenerally in the area of the housing where tangential velocitycomponents are at a minimum so that centrifugal force and separatingelficiencies become quite low. This driving fluid, which may be steam,air or any desired gas, enters the housing through tube 45, beingdischarged in through the upper portion 46 of member 43, and from thenceoutwardly through a plurality of circumferentially arranged nozzles 47.As best seen in FIG.12, these nozzles are positioned to direct the fluidreceived from tube 45 in a rotational pattern in the same direction asobtained by the natural flow within the separator. The gas emanatingfrom these nozzles, impinging upon the material within the housing,

locally speeds up the flow and materially increases the tangentialvelocity at the upper axial portion of the housing. Therefore, thecentrifugal force acting upon the particulate material at this criticalarea of the device is substantially raised and a much higher degree ofseparation is obtained. It is unnecessary in accomplishing this toaccelerate the flow of entire mass in the cyclone. Therefore, theauxiliary member 43 acts both to deflect the particulate materialoutwardly toward the annular passage and to increase the velocity ofrotation of the gases near the gas outlet so that the efficiency of theunit is enhanced. Again, the construction is relatively simplenecessitating no moving parts within the separator, and only thedischarge of relatively small quantities of driving fluid through thenozzles 47. Frequently, in industrial installations, there is suflicientWaste heat to produce enough steam to adequately supply the jets 47, sothat the supply of driving fluid is obtained without added operationalexpense. Where gas temperatures or corrosiveness might preclude the useof external blowers or exhausters, no limitations are imposed when localacceleration is induced by the driving fluid.

In many installations, particularly for larger sizes of cyclones, it isadvisable to provide a double passageway for dust laden gas around theexit tube where the clean gas leaves the housing. An arrangement of thistype may be seen, for example, in FIG. 13 where gas outlet tube 50 islocated within a second concentric tubular member 51 which includes astraight cylindrical section 52 well below the entrance to gas outlet50. The upper end of member 51 is in the form of an outwardly flaringfrustoconical element 53 around the gas exit tube to form a bleedpassageway 54. As discussed above, the diverging nature of passageway 54causes it to act as a difluser increasing the pressure at the upper end56 of the bypass.

Depending portion 52 of member 51, being located at the axis of thehousing, receives the central column of gas rising from the bottom ofthe unit. The particulate matter that may have become entrained withthis core of gas will be near its periphery. Therefore, at the entranceto passage 54 the particles will simply enter passage 54 to be conductedto the bottom of the unit, rather than entering gas outlet 50.

In addition, this version of the invention is provided with a secondtubular element 57 around member 51, resulting in a second annularpassageway 58 opening into the upper end 56 of the bypass passage.Diverging sec tion 59 enables the second annular passageway also to actas a diffuser for realizing eflicient pressure recovery.

The annular passageway 53 receives heavily dust laden gas from therotating vortex ring at the inlet to the housing before any of theparticles have had an opportunity to enter the current of gas passinginto outlet 50. Thus immediately upon entering the housing, a portion ofthe gas at the upper end and along the wall of the housing, where theheaviest concentration of dust is encountered, is drawn off into thepassageway 58 between members 57 and 51 to be conducted to the lower endof the housing where the efliciency of separation is at its greatest.Therefore, by having dual entrances, the bypass receives not onlyparticulate material that has circulated through the housing and failedto separate from the gas, but also draws in solid particles close to theinlet to the cyclone.

Where the axial lengths of passageways 54 and 58 are considerable, it ispreferred to include a plurality of openings 60 in the upper wallportion 53 of member 51. This provides for pressure equalization betweenthe two annular bypass passage-ways prior to their entrance into themain bypass conduit. This is desirable to avoid eddy currents andconsequent turbulence and pressure losses from gases entering the bypassat different pressures.

According to the version of FIG. 14, dual bypass openings again areprovided by the main gas outlet 62, frustoconical member 63, and asecond tubular member 64 around the exterior. In addition, a centraldeflecting member 65 is supported at the axis of the tubular membershaving its downwardly convergent portion 66 beneath the entrance to tube62, while its upwardly convergent portion 67 extends the length ofmember 62. This member 65 acts generally in the manner of member 43-described above for the embodiment of FIG. 11, assisting to deflect thesolid particles into the annular passageway 68 provided between members62 and 63. Particles deflected by lower portion 66 have only a shortradial distance to move in entering the bypass 68. The upper portion 67of member 65 also allows a gradual pressure recovery of the gases in theoutlet tube 62 so as to permit improved flow through the gas outlet fromthe separator.

The arrangement of FIG. 15 is somewhat similar to that of FIG. 14 exceptthat the tubular member 69 around gas outlet 76 includes a lowerdivergent-convergent portion 71 in which is supported an axiallydisposed deflector 72, similar in contour to member 65. Therefore, solidparticles are deflected to the wall of element 71 to be transmitted intothe bypass 73. The relatively wide maximum diameter of member 71 assistsin permitting virtually all of the particles to reach a radial positionat least as far from the axis as the mouth of passageway 73. Improvedpressure recovery is obtained not only in a gas outlet of the device,but also in the bypass system by reason of the positioning of member 72in the lower portion 71 of the downwardly extending annular member 69.Again, an outer tubular section 74 is included to provide the secondannular bypass 75 for the rotating vortex within the entrance portion ofthe separator.

Much like the design of FIG. 15 is the construction of FIG. 16 where anadded cylindrical section 76 has been included. This provides withmember 72 a divergent passageway 77 for eflicient diffusion and pressurerecovery. The outwardly flaring surface 78 of member 76 adds anadditional deflector for directing particulate material outwardly to thewall of member 71. Dilfusion and pressure recovery are accomplished inthe divergent passageway between the upper portion of member 76 and theinner wall of member 71.

Provision for injecting a driving fluid for accelerating the gases atthe location of the bypass and clean gas outlet is added to thepreviously described system in the arrangement of FIGS. 17 and 18. Asshown therein, the lower portion 80 of axially disposed member 81 isrecessed at 82 to accommodate a plurality of convergent nozzles 83.These are arranged to discharge in a rotational pattern having the samedirection of spin as the mass of dust and gas within the separator. Inaddition, they are inclined upwardly from the horizontal at an anglebeta of around 30. As seen in FIG. 18, they also are inclined outwardlywith respect to the tangent of the circumference on which they arelocated at an angle gamma in the order of five to fifteen degrees.

The fluid for nozzles 83 is supplied from tube 84 which enters thehousing through gas exit tube 70 and extends downwardly along the axisto the upper portion of member 81. The tube 84 passes through member 81,and suitably connects to an outwardly radiating manifold 85 whichprovides the driving fluid to the various nozzles 83.

When the driving fluid is ejected in a rotational pattern from nozzles83, it entrains a portion of the main gas flow entering member 69- and,being confined initially by the baflle 76, provides this gas with asizable increase in angular velocity. Also, by virtue of the upperinclination of these nozzles, the gas so contacted receives anadditional vertical velocity component. The presence of member 76assures that there is no interference with the main gas flow passing onthe exterior of that member through member 69. The driving fluid, andthe entrained gas therewith, merge with the remainder of the gas withinmember 69 above baflie 76, adding to the angular momentum, pressure andupward velocity of the main body of gas in the outlet. 69.

The efiect of this, first of all, is to augment the etficiency ofseparation by spinning the gases at a more rapid rate in the vicinity ofthe gas outlet to increase the centrifugal force on the particulatematerial, forcing it into the annular bypass opening. Also, the drivingfluid assists in moving the gases through the cyclone separator andeliminates the need for external blowers or exhaust fans for pumping thegas. This movement of the main body of the gas is enhanced by the factthat the fluid injectors are inclined upwardly to give the rising gas aboost toward the exit tube. At the same time, tubular element 76 assuresthat no undue turbulence will be created by the discharge of the drivingfluid. The provision for the driving fluid is particularly importantwhere high temperatures or corrosive gases are encountered and it is notfeasible to use external pumping means.

It can be seen from the foregoing that I have provided an improvedcyclone separator which takes advantage of the natural flow patternwithin the cyclone to increase its efficiency of separation, reduce thepressure losses and assist in pumping the gases to the clean gas outlet.No moving parts are required, and the movement within the separatortakes place automatically. The improvements of this invention arecentered around the area of lowest natural efficiency where the gasesleave the housing.

The foregoing detailed description is to be clearly understood as givenby way of illustration and example only, the spirit and scope of thisinvention being limited solely by the appended claims.

I claim:

1. A device for separating particulate material from a gas comprising achamber having a first end portion provided with outlet means fordischarging gas therefrom, a second end portion tapering inwardly fromsaid first end portion and having an opening for connection to a hopperfor receiving particulate material, an opening into said chamber at saidfirst end for discharging gas therein in a rotational pattern, and abypass between said ends of said chamber, said bypass having an inletadjacent and radially outward of said outlet at said first end of saidhousing, and an outlet in the second end of said housing for dischargingbypassed material in a rotational pattern in said second end portion andarranged to discharge in the same direction of rotation as the dischargefrom said inlet into said chamber, said outlet in the second end eingadjacent said opening in said second end.

2. A device for separating particulate material from a gas comprising a.chamber having a first end, an inlet for heterogeneous material at saidfirst end for discharging into said chamber in a rotational pattern inone direction, an outlet tube at said first end extending axiallytherein, said chamber having an inwardly tapering open second endprovided with an opening adapted for connection to a receptacle forparticulate material, means surrounding said outlet in said first enddefining an annular passageway, a nozzle at said second end adjacentsaid opening in said second end and arranged to discharge substantiallytangentially in the direction of rotation of said inlet to said chamber,and a conduit interconnecting said annular passageway and said nozzlefor conducting material from the region radially outward of said outletin said first end to said nozzle for rotation within said chamber atsaid second end.

3. A device as recited in claim 2 in which said means defining anannular passageway includes difiuser portions for increasing the staticpressure of gas received therein, said difiuser portions including apassageway of divergent cross sectional area.

4. A device as recited in claim 2 in which said inlet to said chamberincludes a scroll having a bottom wall intersecting the exterior wall ofsaid housing along a substantially helical line inclined toward saidsecond end of said chamber.

5. A device as recited in claim 2 in which said outlet tube at saidfirst end of said chamber isdivergent out- 12 Wardly from said chamberand includes an outer surface adjacent the inlet thereto that isinclined outwardly from the inner wall of said tube away from saidentrance.

6. A device as recited in claim 2 including in addition means fordischarging additional fluid in a rotational pattern similar to therotational patterns from said inlet and said nozzle, and at a locationadjacent the axis of said chamber and the entrance to said outlet tube.

7. A device as recited in claim 2 including in addition an axiallydisposed deflector in said chamber for deflecting particulate materialtoward said annular passageway.

8. A device as recited in claim 2 including in addition a second annularpassageway circumscribing said first mentioned annular passageway andcommunicating with said conduit.

9. A device as recited in claim 2 in which said nozzle is inclinedtoward said opening at said second end.

10. A device as recited in claim 9 in which the angle of inclination ofsaid nozzle, with respect to the axis of said chamber is within therange of from about 70 to about 11. A device for separating particulatematerial from a gas comprising a chamber having a first end, an inletmeans at said first end for discharging into said chamber in a helicalpattern, an outlet for said chamber at said first end, said chamberhaving an inwardly tapering open second end opposite from said first endand provided with an opening for receiving separated particulatematerial, and means for increasing the velocity of rotation within saidchamber, said means including a bypass having an annular diffuser havingan opening around said outlet at said first end and a divergentpassageway beyond said opening, and a means for conducting material fromsaid opening to said opposite end of said housing adjacent said openingin said opposite end for discharge therein tangentially and toward saidopening in said opposite end.

12. A device for separating particulate material from a gas comprising achamber having a first end, an inlet scroll at said first end fordischarging within said chamber in a rotational pattern, a gas outlettube at said first end extending axially into said chamber, said chambertapering inwardly toward a second end portion opposite from said firstend, said second end portion being provided with an opening adapted forconnection to a receptacle for particulate material, a second tube atsaid first end circumscribing said first tube for defining therewith anannular passageway, a conduit connected to said passageway and includinga nozzle discharging in said second end portion of said housing in arotational pattern, and means adjacent said tubes for introducing adriving fluid into said chamber in a rotational pattern for locallyincreasing the velocity of rotation in the vicinity of said tubes.

13. A device as recited in claim 12 in which said annular passagewaydefines a diffuser for increasing the static pressure of gas receivedtherein.

14. A device as recited in claim 12 including, in addition, a third tubecircumscribing said second tube for defining a second annular passagewaytherewith, said second annular passageway communicating with saidconduit.

15. A device as recited in claim 14 in which each of said annularpassageways defines a diffuser for increasing the static pressure of gasreceived therein.

16. A device as recited in claim 14 in which said second tube isprovided with a plurality of apertures through the wall thereof adjacentthe connection thereof to said conduit for thereby providing means forcommunication between said annular passageways for equalizing thepressures therein.

17. A device as recited in claim 14 in which said second tube extendsinto said chamber beyond the entrance to said first tube, an axiallydisposed member and a battle being located inwardly of said first tubeand substantially within said second tube.

18. A device as recited in claim 12 in which said means for introducinga driving fluid into said chamber includes a member axially disposedwith respect to said tubes and having an upwardly converging upperportion and a downwardly converging lower portion, said lower portionhaving a recess therein and being provided with a plurality of nozzlesin said recess, said nozzles being arranged to discharge rotationallyabout the axis of said member and inclined upwardly toward the upper endof said chamber.

19. A device as recited in claim 18 including, in addition, a bafliecircumscribing said axially disposed member at the location of saidrecess and said nozzles, said baflie being frustoconical in form andhaving an outwardly flaring lower edge portion.

20. A device as recited in claim 14 in which said second tube includes asection divergent toward said first end of said chamber from a locationwithin said chamber, and includes an additional and adjacent sectionconvergent toward said one end of said chamber.

21. A device for separating particulate material from a gas comprising achamber of substantially circular cross section,

said chamber having a first end,

an inlet means at said first end for discharge of a mixture of gas andparticulate material in a helical pattern,

an outlet tube extending axially into said first end,

said chamber having an inwardly tapering second end opposite from saidfirst end,

said second end terminating in an opening for receiving separatedparticulate material, and means for increasing the velocity of rotationwithin said chamber,

said means including an annular difiuser circumscribing said outlettube,

said annular diffuser having an inlet opening and a passageway ofdivergent cross sectional area extending therefrom,

14 a bypass passageway connected to said diffuser for receiving materialcollected therein,

said bypass passageway extending exteriorly of said chamber to saidsecond end, said bypass passageway having an outlet at said second endadjacent said opening in said second end, said outlet discharging in arotational pattern about the periphery of an open portion of saidchamber, and being inclined at an acute angle with respect to the axisof said chamber for directing the discharge therefrom toward saidopening in said second end.

References Cited in the file of this patent UNITED STATES PATENTS604,871 Allington May 31, 1898 1,231,371 Jones June 26, 1917 1,235,174Williams July 31, 1917 1,265,763 Fender May 14, 1918 1,267,715 TutweilerMay *28, 1918 1,281,238 Wegner Oct. 8, 1918 1,288,126 Muller Dec. 17,1918 1,581,462 McSweeney Apr. 20, 1926 1,753,502 Clark Apr. 8, 19301,990,943 Home et al Feb. 12, 1935 2,039,115 Rief Apr. 28, 19362,152,114 Van Tongeren Mar. 28, 1939 2,153,026 Ringius Apr. 4, 19392,414,641 French Jan. 21, 1947 2,482,362 Park Sept. 20, 1949 2,857,980Van Rossum Oct. 28, 1958 FOREIGN PATENTS 2,818 Great Britain Feb. 21,1890 236,371 Germany July 4, 1911

